Arc lamp



April 8, 1930 c. LEOTY ARC LAMP Filed Feb. 26, 1925 5 Sheets-Sheet 1 INVENTOR LAWRENCE C. LEOTY ATTORNEY April 1930- y L. c. LEOTY 1,753,242

ARC LAMP File F 26. 1925 s Sheets-Sheet 2 7 Q ummmm j m1 r mum/Tap. m WRE/VCE c. L 0 7).

April 8, 1930.

L. C. LEQTY ARC LAMP il 1925. I5 Sheets-Sheet 3 V T g/U09. LAWRENCE (Fr-507 ATTORNEY Patented Apr. 8, 1930 PATENT oF'FICE LAWRENCE o. LEOTY, or DAYTON, 01110 ABC LAM]? Application filed February 26, 1925. Serial No. 11,745.

This invention relates to are lamps and more particularly to an arc lamp designed for use in connection with photographic work.

One object of the invention is to provide an arc lamp of this character which will be simple in its construction, inexpensive to manufacture and of light weight.

A further object of the invention is to provide such an arc lamp with a simple, easily constructed device for controlling the flow of current to the carbons.

A further object of the invention is to provide a lamp having means for gradually feeding the adjustable carbon toward the fixed carbon; and further to provide such a feeding means which will be controlled by an alternating current passing through the lamp circuit.

Other objects of the invention will appear as the device is described in detail.

In the accompanying drawings Fig. 1 is a perspective view of an arc lamp embodying my invention and its supporting structure; Fig. 2 is a perspective view of'the reflector; Fig. 3 is a diagrammatic sectional view of the reflector; Fig. 4 is a perspective View of the casing for the resistance elements; Fig.

5 is a front elevation of the lamp; Fig. 6 is a vertical sectional view taken centrally of Fig. 5; Fig. '7 is a diagram of the circuit of the lamp; Fig. 8 is a sectional detail view of one of the rheostat coils and a connecting device therefor; Fig. 9 is a detail View of a portion of the casing for the rheostat showing the terminals for the circuit; Fig. 10 is a transverse sectional view taken through the rheostat coils; Fig. 11 is a vertical sectional view of the carbon feeding device; Fig. 12 is a sectiontaken on the line 12-12 of Fig. 11; Fig. 13 is a section taken on the line 13-13 of Fig. 11; Figrld is a side elevation of the clutch member; Fig. 15 is a section taken on the line 1515 of 14; Fig. 16 is a diagrammatic view of a modified circuit arrangement.

In these drawings I have illustrated one embodiment of my invention and have shown the same as comprising a main frame 1 which, in the present instance, is pivotally supported on the arms of a yoke 2 which in turn is adapted to be mounted on a suitable supporting structure, such as a stand 3. Extending forwardly from the frame are suitable supporting devices for the carbons. As here shown, the lower normally fixed carbon is supported in a bracket 5 rigidly secured to but insulated from the frame 1 and the carbon is held in position in this bracket by a clamping device 6. The upper carbon is adjustably supported in a casing 7 rigidly secured to and insulated from the frame 1 and forming a support for the feeding mechanism for the carbon, as will be hereinafter described. Rigidly secured to the frame and extending forwardly therefrom is a housing or reflector 8 into which the carbons project and which serves to direct the light from the arc in the desired direction. In the present instance, I have provided a shield 9 which may be so positioned with relation to the arc that the only indirect rays will be projected from the reflector or it may be so positioned that direct rays will be projected therefrom. As here shown, this shield comprises an elongated vertically arranged plate of metal adjustably mounted at its upper and lower ends on rods 10 which are slidably mounted in the side walls of the housing 8 and are connected one to the other at one side of said housing. as shown at 11, to provide a U-shaped structure, so that they may be readily ioved in unison to adjust the shield with relation to the arc. Further, the connection of the shield with the rods is an adjustable one. and a knob 12 is provided to permit the shield to be moved relatively to the rods, thereby enabling any desired adjustment thereof to be secured. I have also shown the lamp as provided with a frame 13 projecting forwardly from the upper end of the main frame 1 and from which a screen 14 may be supported. a

The'rheostat or current controlling device is mounted on that side of the frame 1 opposite the carbon supporting devices. here shown, this current controlling device is arranged within a housing 15 preferably formed from a sheet of metal, the end portions of which are bent at right anglesto the intermediate portion to provide a three .PLS 9 sided casing, the edges of the side walls of which are rigidly secured to the frame 1. E22

'tendingtransversely across the upper and lower ends of the casing 15 are supporting plates 16 adapted to support the controlling device within the casing. These plates are in the form of strips of sheet metal rigidly secured, respectively, to the upper and lower edges of the side walls of the casing in any suitable manner. Ordinarily a rheostat in a lamp of this kind comprises four coils arranged in pairs, the coils of each pair being arranged end to end, the inner ends of the coils of each pair being connected with one side of the circuit and the outer ends of the coils of each pair being connected with the other side of the circuit, and means being provided whereby a part or all of the coils may be connected in the circuit in parallel. I have provided a rheostat by means of whic" the same results may be secured but which is much simpler in its construction, lighter in weight and less expensive than the old form.

My rheostat consists of two elongated coils ant c *ra o a c i l' as si 11 c1- 17 l 18 a1 ng d sid by side, how 1 agrammatically in Fig. 7. Each of these coilscomprises a continuous winding mounted on a hollow core 19 of porcelain, or other suitable insulating material. Extending through the hollow core 19 is a metallic tube 20, the ends of which project beyond the core and through openings in the supporting plates 16 of the casing 15 and the outer portions thereof are turned down or crimped onto the supporting plates to secure the coil in position. One of the windings at or near the center of each coil is drawn outwardly, as shown at 21, and connected with one side of the circuit. Preferably a clip 22 is clamped on the loop of wire which is drawn out of the coil and so as to provide an eye to receive a binding post or bolt 23 by means of which the loop may be connected with a conductor 24 which leads to one of the carbons. It will be noted that the same binding p st connects the intermediate portions of both coils with the same conductor, thus each coil is divided at its center and I have in effect four separate coils arranged in pairs. The outer ends of each of the coils is connected with a bin ding post, there being two of these posts, 25 and 26. Preferably the wires projecting from the outer ends of each coil are brought together in a clip 27 which is adapted to en gage the binding post, thus forming a ready means for connecting the coil in the circuit. The binding posts 25 and 26 are separate and oneof them is connected with the conductor 28 forming a part of the main circuit. The two binding posts may be connected together so as to connect all the coils in the circuit in parallel, in any suitable manner and, as here shown, a short flexible conductor 29 is connected to one of the binding posts and is provided at its end with a clip by means of which it may be attached to the other binding post. The other branch 30 of the main circuit is connected with a binding post 31 from which the circuit leads to the normally fixed carbon, which is shown at 32. The conductor 24, which is connected with the intermediate portions of the two coils l7 and 18, leads to the upper or adjustable carbon 33. Consequently the current will flow through the conductors and through the carbons 32 and 33 and the flow of current maybe regulated by cutting in one or both of the double coils 17 and 18.

In order to advance the upper carbon 33 gradually and to maintain a continuous arc, I have provided a feeding device which is controlled by a solenoid connected in circuit with the carbons. To this'end the supporting device 7 for the upper carbon is in the form of a casing, the top and bottom walls of which are provided with guide openings 34 in which the carbon is slidably mounted, these openings being preferably provided with brass bushings cast therein. Mounted within the casing 7 is a clutch member, here shown in the form of a washer clutch 35 through which the carbon extends and which, when in a slightly tilted position, will grip the carbon and hold the same against lengthwise movement but when moved into substantially horizontal position will release the carbon and permitit to move downwardly by gravity. The position and operation of this clutch member is controlled by a solenoid which is mounted on the top wall of the casing 7 and comprises a coil 36 Which is wound about a tube 37 which is supported at its lower end in 1 an opening in the top wall of the casing 7 and which has secured to its upper'end a cap or supporting member 38 which is rigidly secured to and insulated from the frame mem her 1. Preferably the ends of the tube 37 are cast in the top plate of the casing and in the cap 38, respectively, and, as here shown, the

cap 38 has a boss 39 extending into the endportion of thetube to reinforce the same and prevent its distortion by alternate contraction and expansion. Slidably mounted in the tube 37 within the coil 36 is the core or armature 10 for the solenoid. This core is preferably of the laminated type and has pivotally connected to its upper end a plunger 41 which fits snugly within the tube and may be formed of self-lubricating material, such as a graphite composition, and which serves not only as a lubricant and guide for the core but also cooperates with the closed end of the tube to form a dash pot which will cushion the movement of the core. The lower end of the core is provided with a stem 42 which projects into the casing 7 and is operatively connected with the clutch member 35. In the present construction this connection is in the form of a fiat spring 43 one end of which is rigidly secured to the clutch or washer 35 at a point spaced from the edge thereof, as shown at 44. The intermediate portion of the spring extends loosely through a guideway 45 formed at the edge of the washer or 3 clutch member and the outer end of the spring is slotted, as shown at 46 to receive the solenoid core. The spring may be retained on this stem in any suitable manner, as by means of a cotter pin 47. The casing has inwardly extending ribs or projections 48 to retain the clutch member in proper relation to the bearings and core. The solenoid being connected with the circuit for the carbons it will be obvious that the movement of the core will be controlled according to the flow of current through the carbons. VVhenthe carbons are in their properly spaced positions the flow of current through the coilwill hold the core in a retracted position and when in this position the core will hold the clutch member in operative engagement with the carbon. As the carbons are consumed and the resistance at the arc increases the flow of current through the solenoid coil decreases, thereby permitting the core to move downwardly. This feeding device may be used with elther direct current or alternating current and when used with direct current the operation of the feeding device is in many respects similar to the feeding devices now used, that is, as the magnetic strength of the solenoid coil decreases, due to the increased resistance at the arc, the core will move downwardly, thus advancing the carbon, and when the lower edge of the washer clutch engages the bottom of the casing 7 the further movement of the core will release the carbon and perm t 1t to drop downwardly into engagement with the lower carbon, thus restoring the circu t and again fully energizing the solenoid coil and causing the solenoid core to be retracted, thereby lifting the clutch member and the carbon and again separating the two carbons and establishing the arc, or as it is commonly called, pulling a new arc. With this operation a continuous arc cannot be secured as the are must be interrupted and a new are pulled upon each feeding operation. lVhen it has been attempted to use a feeding device of this kind with alternating current heretofore, much difliculty has been experienced due to the vibrations set up in the core by the alternations of current. Various means have been proposed to eliminate or avoid the effect of these vibrations but, in the present devlce, I utilize the vibrations thus set up in the core to produce a gradual adjustment of the upper carbon and am thus enabled to provlde a con tinuous are which is not interrupted during the feeding of the carbon. When the arc is normal and the solenoid is fully energized the core will be held in a retracted position, in which a minimum of vibration will occur and which may be termed a neutral position because the pull on the opposite ends of the core will be substantially equal. The spring 48 through which the core is connected with the washer clutch is so regulated that it will vibrate in unison with the vibrations imparted to the core by the alternating current when the core is in this neutral position and the vibrations will thus be absorbed by the spring and will not be transmitted to the washer clutch or at least the amount of vibration transmitted to the clutch will not be suflicient to release the carbon. l/Vhen the magnetic strength of the solenoid coil decreases, due to the increased resistance at the are, the core will move out of this neutral position and as it does so the vibrations imparted thereto by the alternating current will vary and will become greater in length and more or less irregular in character so that the spring 43 can no longer vibrate in unison therewith and the vibrations will betransmitted to the washer clutch and will serve to quickly move the clutch into and out of gripping engagement with the carbon. Upon each of these movements of the clutch the carbon will be permitted to advance a slight distance only because the clutch is quickly restored to its gripping position but the continued vibrations of the core will cause the carbon to be fed downwardly, toward the fixed carbon, until the distance between the carbons has been so reduced as to restore the normal arc and the full flow of current through the solenoid coil, thereby again retracting the core to its neutral position and retaining the carbon against further movement until it has been again consumed to such an extent as to decrease the flow of current and cause a repetition of the feeding operation. The casing 7 within which the clutch mechanism is enclosed serves not only to protect this mechanism from injury and to exclude dirt therefrom, but also serves to deaden any sound or noise which may result from the operation of the feeding mechanism. This casing may be provided with ribs 48'to retain the clutch member in proper relation to the carbon bearings and to the core or reciprocatory plunger of the solenoid. It will be noted that it is not necessary that the clutch washer should move downwardly into contact with the bottom of this casing but it will be actuated while in an intermediate position by the irregular vibrations of the core, due to pulsations of an alternating current, in such a manner as to cause the carbon to be advanced.

The connection between the resistance coils and the solenoid, as shown in Fig. 7 is defied arrangement of the circuit which is adapted more particularly for use in moving picture work. As there shown, the resistance coil 49 is permanently connected with the circuit and an intermediate winding of that coil is connected by a conductor 50 with a solenoid coil 36, in the manner above described. A second resistance coil 51, which is provided with a connecting device 52 by means of which it may be connected into the circuit, has one of its intermediate windings connected by a conductor 53 with an intermediate winding of the solenoid coil. In practice this second resistance coil will be connected with the outer windings only of the solenoid coil so that the current will not pass through the entire coil and will not increase the lifting capacity of the coil in proportion to the amount of current passing to the carbons, thereby providing a very even uniform light which will not flicker, these characteristics being essential for moving picture work.

WVhile I have shown and described certain embodiments of my invention I wish it to be understood that I do not desire to be limited to the details thereof as various modifications may occur to a person skilled in the art.

Having now fully described my invention, whatI claim as new and desire to secure by Letters Patent, is:

1. In an arc lamp, separate supporting devices for two carbons, one of said devices comprising a clutch to engage its carbon and support the same normally in spaced relation to the other carbon, a solenoid having a coil connected in circuit with said carbons and a core slidably mounted in said coil so that the vibrations imparted thereto by an alternating current passing through said coil will vary as the magnetic strength of said coil varies and means for so connecting said core with said clutch that the vibrations imparted to said core when said coil has substantially its full magnetic strength will not affect said clutch but the vibrations imparted to said core when said magnetic strength of said coil has decreased to a predetermined extent will actuate said clutch to gradually feed its carbon toward said other carbon.

2. In an arc lamp, separate supporting devices for two carbons, one of said devices comprising a clutch to engage its carbon and support the same normally in spaced relation to the other carbon, a solenoid having a coil connected in circuit with said carbons and a core so mounted in said coil that as the magnetic strength of said coil decreases said to the last mentioned position, thereby causing said clutch to alternately release and grip said carbon.

3. In a carbon feeding mechanism for an arc lamp, a washer clutch to engage the carbon, a solenoid comprising a coil connected with said carbon, and a core mounted in said coil for vibratory movement under the influence of an alternating current passing through said coil, and a flat spring connected with said washer clutch, extending laterally beyond the same and connected at its outer end with said core.

4. In a carbon feeding mechanism for an arc lamp, a washer clutch to engage the carbon, a solenoid comprising a coil connected. in circuit with said carbon and a core mounted in said coil for vibratory movement under the influence of an alternating current passing through said coil, a flat spring connected at one end with said washer clutch at a point spaced from the edge thereof and extending across the edge of said washer clutch and in supporting engagement therewith but being free to move relatively thereto, and means for connecting the outer end of said spring with said core.

5. In an arc lamp, a main frame, carbons mounted on said frame, a feeding device for one of said carbons, a reflector extending about the adjacent ends of said carbons, a supporting device mounted in the side walls of said reflector for transverse adjustment with relation to said carbons, and a shield carried by said supporting device and movable therewith into and out of line with the arc.

6. In an arc lamp, a main frame, carbons supported on said main frame, a carbon feeding device, a reflector casing rigidly secured to said main frame and extending about the adjacent ends of said carbons, rods slidably mounted in the side walls of said housing, extending beyond one wall thereof and con-v nected one to the other, and a shield adjustably mounted on said rods for adjustmerd therewith or relatively thereto.

7. In an arc lamp, a main frame, a carbon supporting structure mounted on and insulated from said main frame and comprising a closed casing having bearings in which a carbon is slidably mounted, a solenoid mounted on said casing and comprising a core having a part extending into said casing, a clutcn member mounted in said casing and engaging said carbon, and an operative connection between said part of said core and said clutch member.

8. In an arc lamp, a main frame, a carbon supporting structure mounted on and insulated from said main frame and comprising a closed casing having bearings in which a carbon is slidably mounted, a solenoid mounted on said casing and comprising a core having a part extending into said casing, a clutch member mounted in said casing and engaging said carbon, a spring having one end rigidly secured to said clutch member at a point spaced from the edge thereof and having its intermediate portion arranged normally in supporting engagement With the edge of said clutch member but movable with relation thereto and having its other end connected. with said part of said core.

9. In an arc lamp, a main frame, a carbon supporting structure mounted on and insulated from said main frame and comprising a closed casing having bearings in which a carbon is slidably mounted, a solenoid mounted on said casing and comprising a core having a part extending into said casing, a clutch member mounted in said casing and engaging said carbon, and an operative connection between said part of said core and said clutch member, said casing having inwardly extending projections to retain said clutch member in proper relation to said bearings and said core.

In testimony whereof, I afiix my signature hereto. 

